Halo 4 in development for two years

In a panel discussion at Comic-Con reported by GameSpot, Halo franchise boss Frank O'Connor said it was a relief to announce the 2012 Xbox 360 exclusive at E3 last month because the team has been working on it in "relative secrecy for a couple of years".

Halo's Covenant-beating hero will appear "changed" in Halo 4. And there's a story behind his new look – yet to be revealed.

Some time has passed since the events of Halo 3, when the Chief finished the fight. Halo 4 opens with him floating through space towards an alien planet. "A lot of things have changed in that intervening period," O'Connor has teased.